<!doctype html>
<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=1198135
-->
<html><head>
<title>Test for Bug 1198135</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css">
<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1198135">Mozilla Bug 1198135</a>
<style>
.example {
	perspective: 100px;
	height: 300px;
	width: 300px;
	overflow-x: hidden;
	overflow-y: auto;
	border: 1px solid blue;
}

.example__group {
	position: relative;
	transform-style: preserve-3d;
    height: 300px;
    top: 0;
}
.example__layer {
	position: absolute;
	top:0;
	left: 0;
	right: 0;
	bottom: 0;
}
.layer--a {
	box-shadow: inset 0 0 0 1px red;
}
.layer--b {
	box-shadow: inset 0 0 0 1px blue;
	transform: translateZ(50px) scale(.45);
}
.layer--c {
	box-shadow: inset 0 0 0 1px green;
}
.layer--d {
	box-shadow: inset 00px 0 0px 1px orange;
	transform: translateZ(50px) scale(.45);
}
.layer--e {
	box-shadow: inset 00px 0 0px 1px orange;
	transform: translateZ(50px) scale(.45) translateY(300px);
}
</style>
</head>

<body>

<div class="example" id="first">
  <div class="example__group">
    <div class="example__layer layer--a"></div>
    <div class="example__layer layer--b"></div>
  </div>
  <div class="example__group">
    <div class="example__layer layer--c"></div>
    <div class="example__layer layer--d"></div>
  </div>
</div>

<div class="example" id="second">
  <div class="example__group">
    <div class="example__layer layer--a"></div>
    <div class="example__layer layer--b"></div>
  </div>
  <div class="example__group">
    <div class="example__layer layer--c"></div>
    <div class="example__layer layer--e"></div>
  </div>
</div>

<script>
  is(document.getElementById("first").scrollHeight, 600, "Scroll height should be computed correctly");
  document.getElementById("first").scrollTop = 150;
  is(document.getElementById("first").scrollHeight, 600, "Scroll height should be a constant when scrolling");

  // The true height is 727.5 and we don't always snap the same direction.
  isfuzzy(document.getElementById("second").scrollHeight, 728, 1, "Scroll height should be computed correctly");
  document.getElementById("second").scrollTop = 150;
  isfuzzy(document.getElementById("second").scrollHeight, 728, 1, "Scroll height should be a constant when scrolling");
</script>

</body></html>
